In the passage, 'secret stabs' stands for:

Explanation

Anonymous lampoons and satires are the 'secret stabs'.

Note: Passage II is from Addison's Spectator No. 23 (1711) on lampoons and satire, summarised here. Nothing more betrays a base, ungenerous spirit than 'the giving of secret stabs to a man's reputation'. Lampoons and satires written with wit are 'like poisoned darts', which wound incurably. The only excuse for ill-natured satirists is that their wounds are imaginary, an excuse he dismisses. Most troubling is that wit and humour, in ill-natured hands, make virtue and merit the objects of ridicule and buffoonery.